Engines may use various forms of fuel delivery to provide a desired amount of fuel for combustion in each cylinder. One type of fuel delivery uses a port injector for each cylinder to deliver fuel to respective cylinders. Still another type of fuel delivery uses a direct injector for each cylinder.
Further, engines have also been described using more than one injector to provide fuel to a single cylinder in an attempt to improve engine performance. Specifically, in US 2005/0155578 an engine is described using a port fuel injector and a direct injector in each cylinder of the engine.
Another approach utilizing multiple injection locations for different fuel types is described in the papers titled “Calculations of Knock Suppression in Highly Turbocharged Gasoline/Ethanol Engines Using Direct Ethanol Injection” and “Direct Injection Ethanol Boosted Gasoline Engine: Biofuel Leveraging for Cost Effective Reduction of Oil Dependence and CO2 Emissions” by Heywood et al. Specifically, the Heywood et al. papers describes directly injecting ethanol to improve charge cooling effects, while relying on port injected gasoline for providing the majority of combusted fuel over a drive cycle.
However, the inventors herein have recognized a problem with such approaches. Specifically, different combustion characteristics may be produced depending on the relative injection amounts from different injectors or depending on the variation in fuel blends from different injectors. For example, different injectors may have different timing, different targeting, different octanes, and/or different oxygen contents.
Thus, to provide improved operation of the engine and to account for at least some of these differences, the setting of various engine parameters may be adjusted in response to the relative delivery amounts or timing between different injectors both delivering fuel to a common cylinder. In one approach, a parameter affecting flow through the engine may be adjusted, such as a charge motion control valve, an exhaust gas recirculation valve, a port deactivation valve, and/or a throttle valve. In this way, for example, different charge motion control valve positions may be used for different relative injection amounts or timing resulting in more or less charge motion to match to current conditions.